The leaf of the sugarcane plant is divided into two parts: sheath and blade, separated by a blade joint. The sheath, as its name implies, completely sheaths the stalk, extending over at least one complete internode.

The leaves are usually attached alternately to the nodes, thus forming two ranks on opposite sides. The mature sugarcane plant has an average total upper leaf surface of about 0.5 square meter and the number of green leaves per stalk is around ten, depending on variety and growing conditions.

The blade joint is where two wedge shaped areas called "dewlaps" are found. The leaves are numbered by Kuijper's system, as quoted by Casagrande (1991). The first leaf from top to bottom of the stalk with clearly visible dewlap is designated as +1. Downwards they receive, in succession, the numbers +2, and +3. The "top visible dewlap" leaf (+3) is a diagnostic tissue that is frequently used in the evaluation of the nutritional status.